This disclosure is directed to systems and methods for measuring velocity errors and reducing torque disturbances in movable image carriers of image forming devices.
A variety of systems and methods are conventionally used for velocity control for movable image carriers, such as photoreceptors or intermediate transfer belts or drums, in image forming devices. Prior solutions include use of highly inertial photoreceptor drums or highly inertial photoreceptor belt rollers that reduce the effects of disturbances. Further systems and methods can include classically designed velocity feedback systems supplemented by a periodic feed-forward control scheme.
Speed of a movable image carrier motor drive unit must generally be tightly controlled. Generally, movable image carrier velocity sensors sense any increase or decrease in velocity of the movable image carrier motor drive unit. A motor control device reacts to readjust the speed of the movable image carrier motor drive unit and, thus, the movable image carrier.
U.S. Pat. No. 7,379,680, entitled “Systems and Methods for Determining Feed Forward Correction Profile For Mechanical Disturbances In Image Forming Devices” by James Calamita, which is commonly assigned, discloses a control system to automate and/or adapt feed-forward correction (FFC) profile to match precisely the timing and nature of a torque disturbance in a transfer subsystem, which may reduce or substantially nullify torque disturbances, such as, for example, torque disturbances caused by a photoreceptor belt seam passing over an acoustic transfer assist (ATA) unit in a photoreceptor belt-based transfer subsystem in an electrophotographic and/or xerographic image forming device. A learning algorithm is also applied using a correlated model of system dynamics to compensate for torque disturbances in mechanical systems, such as, for example, transfer subsystems, in image forming devices.
U.S. Pat. No.7,444,101, entitled “Systems and methods for improving belt motion and color registration in an image forming device” by James Calamita, which is commonly assigned, discloses a method and system of correcting a medium velocity error in a photoreceptor belt of an image forming device with a controller. A velocity error of the photoreceptor belt is measured when the medium is used in the image forming device, the velocity error comprising a velocity error due to the image forming device dynamics and a velocity error due to torque disturbance on the photoreceptor belt. A high frequency velocity error is filtered from the measured velocity error, removing the velocity error due to the image forming device dynamics from the measured velocity error to produce a remaining velocity error. The remaining velocity error is converted to torque disturbance. A correction factor is determined on the basis of the torque disturbance, and the medium velocity factor is corrected on the basis of the determined correction factor.
U.S. Pat. No. 7,157,873, entitled “Systems and Methods for Reducing Torque Disturbance in Devices Having an Endless Belt” by Kevin M. Carolan, which is commonly assigned, discloses a control system to compensate for motion disturbances which may cause defects in multi-color output images produced by image forming devices. The system may include a controller that determines when a torque disturbance is expected to occur and controls the photoreceptor belt motor drive unit with a compensation amount that may be retrieved from a data structure. This compensation amount from the data structure may be adjusted via a gain factor and may be combined with the output of a closed loop compensator at a summation point, to attempt to minimize the misregistration effect produced by the torque disturbance in the output images produced by the image forming device. A timing methodology is employed to anticipate the onset of a disturbance, and via the controller, attempts to insert an opposing profile that causes the photoreceptor belt motor drive unit to generate an opposing torque to substantially nullify the disturbance. The amplitude of a correction profile, corresponding to the amplitude of the disturbance, is manually adjusted to attempt to minimize the effects of the disturbance on the produced output images, for example, the color-to-color registration error. The controller monitors the onset of the disturbance or predicts the onset of the disturbance based on sensed photoreceptor belt position and encoder timing. Correction factors for the current operating state of the transfer subsystem in the image forming device are obtained substantially through a trial and error method.